Which is better: holding a second congregation in the mosque for those who missed the first, or praying in congregation at home with one's family? And is this in accordance with the Sunnah?

If a mosque does not have a regular imam, then it is not disliked by scholarly consensus to hold a second congregational prayer in it. The worshipper is given the choice between praying there or at home. However, if a mosque has a regular imam and is not (regularly) frequented (by worshippers), then the majority opinion is that a second congregational prayer in it is disliked. Ahmad, Ishaq, and Dawud, on the other hand, held the view that it is not disliked, and in this case, praying outside the mosque is better.